1. Technical Field
The present invention relates to a mobility measuring apparatus for measuring a mobility of carriers in a semiconductor, a method therefor, and a resistivity measuring apparatus for measuring an electric resistivity of a semiconductor and a method therefor.
2. Related Art
A Hall measurement is generally carried out for measurement of mobility of carriers in a semiconductor and an electric resistivity of a semiconductor.
Also, Fu, et al. (Y. Fu, M. Willander, Z.-F. Li and W. Lu: “Electron mobilities, Hall factors, and scattering processes of n-type GaN epilayers studied by infrared reflection and Hall measurements.” Physical Review B Vol. 67(2003) p. 113313) discloses a method of determining the decay constant and the density of the carriers using terahertz waves. By this method, terahertz waves of a broad band including the band of a phonon frequency of a semiconductor are radiated onto a sample so as to observe reflection spectra. Subsequently, fitting is carried out so that the observed reflection spectra and the calculated reflection spectra may be matched with each other, whereby the decay constant and the density of the carriers are determined.
Also, as a method of determining the carrier density of a semiconductor by using two terahertz waves, there is a method disclosed in Japanese Patent Application Laid-open (JP-A) No. 2009-145223.
However, the conventional techniques disclosed in the above documents leave room for improvements with respect to the following points.
The Hall measurement is a contact measurement in which a solder is heated to attach electrodes to a sample; and the four terminals are contacted with the electrodes. In order to attach the electrodes, the sample must be processed into a flat plane, so that this will be a destructive test.
Also, according to the technique disclosed in Fu, et al., terahertz waves of a broad band are radiated onto a sample so as to observe reflection spectra, thereby needing a period of time of several ten minutes. Also, in order to match the observed reflection spectra with the calculated values, calculation must be made for each of the observed reflection spectra. Also, for performing fitting, a period of time of several ten seconds will further be needed.
Further, according to the technique of JP-A No. 2009-145223, the relationship between the reflectivity of a semiconductor to a terahertz light and the decay constant of the carriers is not made clear, so that neither the mobility of the carriers nor the electric resistivity can be determined.
The present invention has been made in view of the aforementioned circumstances, and an object thereof is to provide calculation of a mobility of carriers in a semiconductor and an electric resistivity of a semiconductor in a short period of time in a non-destructive manner.